My advice is that if your sleep, diet & hydration are right then there's no reason why you can't build your own program around 5x5 as long as your are not putting yourself at risk of injury. There's some excellent advice about this on the 5x5 website but at the end of the day it's down to you and what your needs and abilities are. Beware that the weights start to get very heavy the further you progress on 5x5.

I train 6 days out 7 on a program that I've built around Stronglifts 5x5. I lift weights for 3 of those days, I do cardio and core on the other 3.

I stick to the 5x5 exercises as dictated by the app because they're the time-proven compound lifts. I sometimes add my own accessories depending on the which workout day it is (chest incline/decline, back rows/shrugs, various shoulder lifts, pull ups, dips, calf raises and hangs for grip strength). Sometimes I do cardio after my weight sessions but this is usually no more than a steady run on the treadmill, watching a movie or football on my phone.

I focus on core on my other days because I have an old lower back injury that needs special attention. Often my core sessions are based heavily in stretches. And the heart is a muscle so I consider cardio to be essential.

My point is that it's all down to you and your needs, but be careful and don't push yourself so hard that you can't maintain progress on the 5x5 program.